We have recently discovered that Nef- and Vif-specific CD8 responses in Indian macaques control viral replication of the highly pathogenic SIVmac239 isolate. Furthermore, Vif-specific CD8+ T cell clones are highly efficient at controlling SIV replication. While Nef has been used in vaccine development, Vif has not been used as a human vaccine immunogen to date. Therefore, we will explore whether Vif-specific CD8+ T cell responses are present in humans that control HIV replication. We will sequence autologous Vif from approximately 30 patients that control HIV replication and then use the HLA types of the patients to predict CD8 epitopes in the patients'autologous Vif sequences. We will also use the sequence of the patients'autologous protein Vif to synthesize 15-mers that overlap by 11 amino acids. We will determine whether CD8+ lymphocytes from our patients respond to minimal optimal peptides and pools of 15-mers using ICS, Elispot and tetramers. Finally, we will determine whether Vif-specific CD8+ lymphocytes control viral replication in a novel Virus Suppression Assay (VSA). For the vaccine studies in macaques, we hypothesize that efficacious CD8+ T-cell responses directed against epitopes in Nef and Vif accompanied by broad Gag-specific CD4+ T-cell responses will control replication of the highly pathogenic SIVmac239 clone. We will vaccinate three groups of 8 macaques with a novel DNAprime/Ad5 boost vaccine regimen encoding Gag, Rev, Tat, Nef and Vif and then challenge them with the clone SIVmac239. These studies could lead to the definition of an additional target for vaccine-induced immune responses. Currently Env, Gag, Pol and Nef are being used in early human trials. Vif is currently not being considered. If we can demonstrate that Vif-specific CD8+ T cells play an important role in control of HIV replication, then Vif could also be included as an important vaccine target. HIV kills more people every year than any other infectious disease. There is an urgent need for a vaccine. We are proposing a novel approach to HIV vaccine development.